I've found that rebuilding the cfg file usually sorts out the stutters on my i7 2600k gtx 970 rig.
I've found that tweaking the fsx-se cfg file worsens performance as opposed to the fsx cfg file which didn't mind being changed so much.
Maybe Dovetail changed how the cfg file works as I don't even see an entry for Highmemfix=1 in there.
I'm not using nvidia inspector either and have my frames set to unlimited.
Water and shadows usually bring my computer to it's knees so I've turned them off and have a much smoother sim.
I'm running with Steve's DX10 fixer too. Aerosoft Airbus, openvfr Europe, HDMesh EU. FSXWX (excellent freeware) for weather injection and REX Soft Clouds.
UK2000 Heathrow, Ringway, John Lennon and Glasgow Airport sceneries. Aerosoft Dublin and Schiphol airports.
All settings in scenery to max apart from water and ground scenery shadows which are set to off.